I know some of my lenses are not considered weather sealed without a filter on the front. I live in the wet, damp, rainy Pacific Northwest and am concerned about exposing the lens to less than dry weather without a filter.

It's not weather sealed even with a filter. It doesn't have a rubber gasket at the mount, and it has far too many control gubbins and sliding surfaces to be weather sealed, without extraordinary effort. OTOH, a decent camera rain coat would probably do the trick - with a high quality filter on the front. I would use my 82mm B+W MRC #007 Protection Clear filter.